The present invention relates to a semiconductor integrated circuit, a card including the semiconductor integrated circuit, and an operating method of the semiconductor integrated circuit. More particularly, the invention relates to a technique effective to make a semiconductor integrated circuit reliably operate even when a communication distance is long.
An IC card having no power supply is being spread and used in various fields such as an automatic ticket gate system, electronic money, and physical distribution management. Power is supplied to the IC card by receiving an RF signal from a reader/writer called a card reader/card writer by an antenna coil of the IC card and rectifying the RF signal by a rectifying circuit. The IC card is called an RFID card for the reason that an RF signal is supplied to the IC card and unique identification (ID) information is stored in a built-in nonvolatile memory.
Non-patent document 1 describes an RFID CMOS tag IC attached to a commodity. The tag IC includes a CMOS full-wave rectifying circuit, a band-gap reference voltage circuit, a booster circuit, an overcurrent protection circuit, a reception demodulator, a transmission modulator, a clock generation voltage control oscillator, a transmission/reception control logic, and a nonvolatile memory. The CMOS full-wave rectifying circuit generates an internal supply voltage VDD from a UHF carrier wave emitted from a reader/writer, and the booster circuit supplies an operation supply voltage to a ferroelectric RAM as a nonvolatile memory.
Non-patent document 1
    Hiroyuki Nakamoto et al, “A Passive UHF RF Identification CMOS Tag IC Using Ferroelectric RAM in 0.35-v Technology”, IEEE Journal of Solid-State Circuits, Vol. 42, No. 1, January 2007, pp. 101 to 109